Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx> Hi DC,There is nothing wrong with your point of view. Modular weight is an issue and a trade off. My coil easily tears down to the cart, primary, coil, and topload. The cart is by far the hardest to deal with even with its caster wheels :-(( It takes two to get it into the car and a big struggle for just myself to get it out in the back porch with two steps to navigate. I chose the cart approach to minimize the setup and I did worry about eddy losses at first. I dont think I would partition things that way for a larger NST farm, at least until I eat some spinach.
Gerry R.
Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>I see what you are saying. My point is to simply use the best possible engineering, ie, not give away any power you don't have to in parasitic losses. You're absolutely correct though --- spark gap losses contribute the greatest losses, heat, light, etc, which is why everyone is running to solid state drivers for many applications.If you take a coil such as yours out to a school, with xmfr direct mounted, you will need a good supply of gorillas to move it about or "lotsa caster wheels"!!On our NST pwr supply boxes we just use handles. If we use multiples of 60 or 120 mA NSTs we put them in separate boxes and "jumper" them together with GTO and simple 1/4 inch bananna plugs/receptacles mounted on delrin plastic plates --- keeping things modular really helps reduce the weight when we haul the coils around for school programs, public demos, etc. It's important to consider this in the very design phase when building a coil. Carrying boat anchors isn't much fun --- been there, done that.Dr. Resonance ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Tuesday, April 18, 2006 1:27 PM Subject: Re: Transformer location/SafetyOriginal poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx> Is it a bad idea?? Maybe and maybe not.Do you get eddy current losses?? Yes! You also get copper losses, sparkgap losses, etc.Are these losses significant?? Depends on how close the metal is to the primary. My 4 NST's are 1.5 feet below the primary. The cases dont touch each other and are only connected together by a one wire connection to minimize eddy currents. Is my power loss significant. I dont think so since I get 86 inch arcs with a 15KV 120ma source (freau factor of 1.9 based on measured real power at the wall of 2KW).The real question, I believe, for each one of us to answer is how much loss is acceptible. Everything in life is a trade off for the most part.Gerry R.> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx> > > > > Bad idea. I've already several reasons on this list why mounting the > nst under the primary is a bad idea but people keep trying to do it > wrong anyway. Magnetic field sweeps upward as well as downward and > will go right thru you aluminum shield to induce currents in your > copper xmfr windings. Also, downward sweeping magnetic fields will > give up power, ie losses, in anything iron, steel, etc below the > primary. Just don't do it --- it's very bad basic engineering!!! > > Aluminum does not stop a magnetic field. In high power Tokamaks they > wind the high current windings on the "outside" of the aluminum > container so the magnetic fields can effect the conductive plasma > inside the container. > > Mount your nst in a box 4-5 ft away from the coil and you will be > miles ahead without losing power or inducing RF currents into your > xmfr windings. > > Dr. Resonance